Knit fabric for apparel

ABSTRACT

An article of apparel includes a multilayered knit fabric structure. The knit fabric structure includes a first knit layer and a second knit layer, and a resilient intermediate knit layer disposed between and coupling with the first knit layer and the second knit layer. The intermediate knit layer has a corrugated shape along a first direction of the intermediate knit layer with consecutive peaks that are oriented in opposing directions such that the peaks comprise a set of first peaks oriented in a first peak direction and a set of second peaks oriented in a second peak direction that opposes the first peak direction. The first peaks of the intermediate knit layer connect with the first knit layer and the second peaks of the intermediate knit layer connect with the second knit layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Patent Application No. 63/295,367, filed Dec. 30, 2021, and entitled “Knit Fabric For Apparel,” the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to knit fabric suitable for use in apparel, and a method of forming the fabric and/or apparel.

BACKGROUND

Apparel such as clothing (e.g., upper body garments including shirts and brassieres, lower body garments including athletic shorts, an article of footwear) can be designed to provide a variety of features depending upon a particular application. Some features that are desirable are comfort, breathability, durability, stretchability and sufficient support and protection for body parts of the user when the article of apparel is worn. For certain applications, it may also be desirable to control a degree of stretch in one or more directions along an article of apparel during use.

It would be desirable to provide a textile article that is lightweight, breathable, and durable, and further provides enhanced levels of stretchability at different locations of the textile article depending upon a particular application of use.

SUMMARY OF THE INVENTION

In example embodiments, a knit fabric structure for an article of apparel comprises a first knit layer and a second knit layer, and a resilient intermediate knit layer disposed between and coupling with the first knit layer and the second knit layer. The intermediate knit layer has a corrugated shape along a first direction of the intermediate knit layer with consecutive peaks that are oriented in opposing directions such that the peaks comprise a set of first peaks oriented in a first direction and a set of second peaks oriented in a second direction that opposes the first direction, the first peaks of the intermediate knit layer connect with the first knit layer and the second peaks of the intermediate knit layer connect with the second knit layer.

In another embodiment, an article of apparel (e.g., a brassiere) includes the knit fabric structure incorporated within the article of apparel.

The knit fabric structure can exhibit auxetic properties (possess a negative Poisson's ratio) or near auxetic properties (possess a Poisson's ratio of approximately zero, whether slightly negative or slightly positive). For example, the intermediate knit layer may be configured to lower the Poisson's ratio of the outer knit layers such that the entire knit structure exhibits a negative Poisson's ratio in response to being stretched in a dimension that corresponds with the direction of consecutive peaks extending along the corrugated shape of the intermediate knit layer.

Methods of forming a multilayered knit structure for an article of apparel are also described herein.

The above and still further features and advantages of the present invention will become apparent upon consideration of the following detailed description of specific embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an example embodiment of a single layer knit structure.

FIG. 2 is a schematic view in cross-section (taken along the course direction of the middle or interior layer) of an example embodiment of a knit structure comprising a plurality of connected layers having auxetic properties as described herein.

FIG. 3A is an enlarged view of a portion of the knit structure of FIG. 2 .

FIG. 3B is an enlarged view of FIG. 3A (i.e., a further enlarged view of FIG. 2 ), in which knit courses are schematically depicted along the wale direction for each of the first and second outer knit layers of the structure.

FIG. 4A is a schematic view of a portion of the knit structure of FIG. 2 in normal, unloaded or unstretched configuration.

FIG. 4B illustrates the knit structure of FIG. 4A under a first degree of tension or load.

FIG. 4C illustrates the knit structure of FIG. 4A under a further degree of tension or load (e.g., a maximum or “lock out” tension).

FIG. 4D depicts a view in plan of an exterior surface of the knit structure of FIG. 4C, showing surface area expansion of the knit structure in a dimension transverse the direction of stretch (tension) being applied to the knit structure.

FIG. 5A is a cross sectional view of the fabric in accordance with an embodiment of the invention, shown in an unloaded state.

FIG. 5B is a cross sectional view of the fabric of FIG. 5A, shown in a state under load.

FIG. 6A illustrates a schematic view of a conventional fabric having a strongly positive Poisson's ratio which results in the fabric contracting in a dimension transverse a dimension in which a load or stretching force is applied to the fabric (i.e., the fabric is in a loaded state).

FIGS. 6B and 6C illustrate schematic views of fabrics formed according to the embodiments described in accordance with the present invention in a loaded state and in which the fabric exhibits a negative Poisson's ratio (FIG. 6B) and a neutral (or slightly positive) Poisson's ratio (FIG. 6C).

FIG. 7 is a brassiere including a knit structure in accordance with an embodiment of the invention.

FIG. 8 is a view of an article of footwear (athletic shoe) including a knit structure formed in accordance with an embodiment of the present invention.

FIG. 9 is a view of an article of apparel (upper body garment) including a knit structure formed in accordance with an embodiment of the present invention.

FIG. 10 is a view of an article of apparel (lower body garment) including a knit structure formed in accordance with an embodiment of the present invention.

Like reference numerals have been used to identify like elements throughout this disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying figures which form a part hereof wherein like numerals designate like parts throughout, and in which is shown, by way of illustration, embodiments that may be practiced. It is to be understood that other embodiments may be utilized, and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents.

Aspects of the disclosure are disclosed in the accompanying description. Alternate embodiments of the present disclosure and their equivalents may be devised without parting from the spirit or scope of the present disclosure. It should be noted that any discussion herein regarding “one embodiment”, “an embodiment”, “an exemplary embodiment”, and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, and that such particular feature, structure, or characteristic may not necessarily be included in every embodiment. In addition, references to the foregoing do not necessarily comprise a reference to the same embodiment. Finally, irrespective of whether it is explicitly described, one of ordinary skill in the art would readily appreciate that each of the particular features, structures, or characteristics of the given embodiments may be utilized in connection or combination with those of any other embodiment discussed herein.

Various operations may be described as multiple discrete actions or operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations may not be performed in the order of presentation. Operations described may be performed in a different order than the described embodiment. Various additional operations may be performed and/or described operations may be omitted in additional embodiments.

For the purposes of the present disclosure, the phrase “A and/or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

The terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous.

A multi-layer knit material or knit structure as described herein comprises a textile construction including a plurality of layers coupled with each other so as to form a structure with useful properties, including enhanced elastic properties that exhibit a Poisson effect, i.e., having auxetic properties or near auxetic properties, in response to the knit structure being subjected to a stretching force (i.e., under load or tension) as described herein. As used herein, the term “auxetic” in relation to the knit structure refers to the knit structure exhibiting a negative Poisson's ratio when stretched in a particular direction of the knit structure. The term “near auxetic” in relation to the knit structure refers to the knit structure with a Poisson's ratio of about zero such that the stretch pattern of the pattern is substantially neutral (explained in greater detail below). By way of specific example, a near auxetic fabric possesses a slightly positive Poisson's ratio close to zero, i.e., a Poisson's ratio of about −0.25 to about +0.25 (e.g., a ratio of from about 0 to about +0.15). The knit material that is formed is resilient—when load or tension is applied, the material moves from a normal, unstretched configuration to an expanded, stretched configuration. When the load is released, the knit material recovers, returning to its normal, relaxed configuration.

The knitting process for forming the knit material comprises interlooping of one or more strands or yarns together to form layers, where the layers are further combined with each other in a manner as described herein. In general, knitting is the method of creating fabric by transforming continuous strands of yarn into a series of interlocking loops, where each row of such loops hangs from the one immediately preceding it. The basic element of a knit fabric structure is the loop intermeshed with the loops adjacent to it both sides and above and below it. An example embodiment of a single layer of knit fabric structure 2 is depicted in FIG. 1 , where the structure 2 includes continuous strands of yarn 4 forming interconnected loops. Loops of a continuous strand are arranged along a row of the structure 2 in what is referred to as the course direction 10 of the knit structure, while the opposing or orthogonal direction of the knit structure to the course direction is referred to as the wale direction 20. Accordingly, courses (i.e., rows of interconnected loops arranged in the course direction) of the knit structure 2 are defined along the wale direction 20 (e.g., first course, second course, third course, fourth course, fifth course, etc.).

Forming a fabric structure via a knitting process can be performed in different ways, including warp knitting and weft knitting. In warp knitting, the yarns generally run lengthwise in the fabric (e.g., tricot, milanese, and raschel knitting). In weft knitting, one continuous thread runs crosswise in the fabric making all of the loops in one course. The knit structure 2 depicted in FIG. 1 is an example of weft knitting. Weft knitting includes both circular knitting and flat knitting. In circular knitting, the fabric is produced on the knitting machine in the form of a tube, with the threads running continuously around the fabric. In flat knitting, the fabric is produced on the knitting machine in flat form, the threads alternating back and forth across the fabric. By way of example, a knit structure can be knitted using a double bed flat knit machine such as a programmable CMS 530 H or CMS 730 S flat knitting machine from H. Stoll GmbH & Co. Further, the knitting machine can comprise a double bed knitting machine to facilitate continuous knitting of the separate layers that connect with each other at selected distances (measured by rows or courses as described herein) along the layers. The knit structure formed herein can also comprise jersey knit layers of fabric material. The multi-layered knit structure described herein can be formed via any suitable knitting process that facilitates the formation of a plurality of interconnected layers having properties as described herein that impart useful Poisson ratio features (e.g., auxetic and/or near auxetic properties) to the knit structure.

In example embodiments of the multi-layer knit structure described herein, the knit structure is formed via a weft knitting process (e.g., circular knit or flat knit) where each layer is knit/constructed at about the same or similar time with the other layers and/or during the same knitting process, with layers being connected with each other at selected intervals of courses of each knit layer as described herein. In other words, one layer of the multi-layer knit structure can be formed and coupled with another layer of the multi-layer knit structure during the forming of the other layer of the multi-layer knit structure (e.g., the layers are formed near simultaneously). Each knit layer can comprise a jersey knit fabric material, where the intermediate knit layer has different elastic properties as the outer knit layers as described herein.

It is noted that, when describing the layers forming the knit structure, the term “yarns” is used. However, it is noted that the layers of the knit structure can be formed with strands, fibers, filaments and/or yarns. The term strand includes a single fiber, filament, or monofilament, as well as an ordered assemblage of textile fibers having a high ratio of length to diameter and normally used as a unit (e.g., slivers, roving, single yarns, plies yarns, cords, braids, ropes, etc.). In a preferred embodiment a strand is a yarn (a continuous strand of textile fibers, filaments, or material in a form suitable for knitting, weaving, or otherwise intertwining to form a textile fabric). A yarn may include a number of fibers twisted together (spun yarn); a number of filaments laid together without twist (a zero-twist yarn); a number of filaments laid together with a degree of twist; and a single filament with or without twist (a monofilament).

Referring to the example embodiment of FIGS. 2 and 3 , a knit structure 100 includes a plurality of jersey knit layers (e.g., 3 layers) connected with each other, where each layer is formed of strands or yarns during the knitting process so as to be separated, individual or distinct from the other layers, where two or more layers are interconnected with each other at certain locations along the knit structure as a result of the knitting process.

The knit structure 100 includes a first shell or outer knit layer 110 that includes a first surface 115 defining an exposed side of the knit structure, a second shell or outer knit layer 120 that includes a second surface 125 defining an exposed side of the knit structure that opposes the first surface 115, and a resilient middle or intermediate knit layer 130 that is disposed and extends between and interconnects with the first and second outer knit layers. The resilient intermediate knit layer 130 has an undulating or corrugated shape that generally defines a sinusoidal or wavy pattern in which the intermediate knit layer 130 connects in an alternating manner with the first outer knit layer 110 and the second outer knit layer 120 at each crest or peak (e.g., at the amplitude) along the corrugated surface of the intermediate knit layer. In other words, the outer knit layers connect with the intermediate knit layer at opposing peaks (i.e., peaks oriented in opposing directions) of the intermediate knit layer. For example, as shown in FIG. 2 , consecutive peaks of the intermediate knit layer 130 are oriented in opposing directions such that the peaks comprise a set of first peaks 132 oriented in a first direction and a set of second peaks 134 oriented in a second direction that opposes the first direction, the first peaks 132 of the intermediate knit layer 130 connect with the first knit layer 110 and the second peaks 134 of the intermediate knit layer 130 connect with the second knit layer 120. As further shown in FIG. 2 , the first and second knit layers are coupled with each other solely or only via connections with the intermediate knit layer 130 (i.e., at the peaks of the intermediate knit layer).

While the knit material structure 100 depicted in the figures comprises a three-layer structure (first and second outer or shell layers, and middle or intermediate knit layer), it is noted that the knit material structure can also include additional layers (e.g., layers between the first and second outer knit layers and/or further layers coupled to either or both of the first and second outer knit layers at the exterior surface of the outer knit layers). The forming of the intermediate knit layer and the coupling of the intermediate knit layer with the first and second knit layers can occur during the forming of each of the first and second knit layers (e.g., each layer is formed at or nearly at the same time, with the coupling of the intermediate knit layer to each of the first and second layers also happening at or about the same time as the first, second and intermediate knit layers are being formed).

The first and second outer knit layers 110, 120 can be formed of the same or similar materials. In an example embodiment, the first and second outer knit layers are identical in how they are formed and in relation to the yarns used to form the outer knit layers (e.g., with the first and second outer knit layers having the same number of courses in general alignment with each other when connected with the intermediate knit layer). Each outer knit layer can be formed with yarns that are non-elastic or harder/less elastic than yarns forming the intermediate knit layer 130. Non-elastic yarns or strands possess no inherent stretch and/or recovery properties by virtue of composition. Alternatively, each outer knit layer can be formed with yarns having the same or similar elasticity as the strands forming the intermediate knit layer. Some non-limiting examples of yarns that can be used to form the first and second outer knit layers include cellulosic fibers (e.g., cotton, bamboo) and protein fibers (e.g., wool, silk, and soybean), polyester fibers (poly(ethylene terephthalate) fibers and poly(trimethylene terephthalate) fibers), polycaprolactam fibers, poly(hexamethylene adipamide) fibers, acrylic fibers, acetate fibers, rayon fibers, nylon fibers and combinations thereof. The first and second outer knit layers can also be formed of one or more elastic materials that can be of the same or similar types as those used to form the intermediate knit layer (as described herein).

The intermediate knit layer 130 is formed with yarns that are elastic and have at least the same elasticity or greater elasticity in relation to the yarns that form the first and second outer knit layers 110, 120. By way of example, elastic strands or yarns forming the intermediate knit layer include an elastomeric material (e.g., a 100% elastic material). Elastic strands or yarns, by virtue of their composition alone, are capable of stretching under stress and recovering to an original size once the stress is released. Accordingly, elastic strands or yarns are utilized to provide a textile with stretch properties. An elastic strand or yarn is formed of rubber or a synthetic polymer having properties of rubber. A specific example of an elastomeric material suitable for forming an elastic strand or yarn is elastane, an elastomeric polyester-polyurethane copolymer (e.g., an elastane yarn commercially available under the tradename SPANDEX). The elastomeric yarns used to form the intermediate knit layer can also comprise covered yarns, such as a single covered yarn or a double covered yarn (DCY), where an elastomeric strand forms the core of single or double covered yarns and is thus covered (e.g., helically wound) by one or more non-elastic strands.

In an example embodiment, the first and second outer knit layers 110, 120 are formed of polyester yarns, while the intermediate knit layer 130 is formed of double covered yarns comprising polyester and elastane (i.e., polyester strands wrapped around elastane strands).

The first and second outer knit layers and the intermediate knit layer are each individual, separate knit layers that are formed together in a single knitting process, where the intermediate knit layer couples the first and second outer knit layers together at the connections or stitch locations (i.e., at the peaks of the intermediate knit layer). The connections or stitch locations between the intermediate knit layer and each of the first and second outer knit layers can be formed in a suitable manner, where one or more yarns formed along a course of the intermediate knit layer wrap around or interconnect with one or more yarns formed along a course of the first and/or second outer knit layer.

As indicated in FIG. 2 and further in FIGS. 3A and 3B, the arrangement of rows or courses (i.e., wale direction) of the knit material for each of the first and second shell or outer knit layers 110, 120 extends in the same direction as the undulating or corrugated pattern formed by the intermediate knit layer 130. For example, courses 140 are schematically depicted along the surfaces of the outer knit layers 110, 120 in FIG. 3B. In contrast, the arrangement of courses (i.e., wale direction) of the knit material for the intermediate knit layer 130 is transverse (e.g., orthogonal or perpendicular to) the arrangement of courses (wale direction) of the knit material for each of the first and second outer knit layers (see FIG. 3A showing wale direction for the intermediate knit layer).

Referring to FIGS. 3A and 3B, the distance D1 between two adjacent and opposing peaks 132, 134 of the corrugated intermediate knit layer 130 defines a distance or course length (i.e., number of courses 140) from a connection or stitch 136 between the intermediate knit layer and the first outer knit layer 110 and a closest connection or stitch 138 between the intermediate knit layer and the second outer knit layer 120. The distance D1 between such consecutive alternating connections or stitch locations (where the intermediate knit layer couples together the first and second outer knit layers) can be defined by a number of rows or courses 140 along the first and second outer knit layers. In example embodiments, the distance or course length D1 is from about 3 courses to about 6 courses measured along each of the first and second outer knit layers. In the example embodiment of FIGS. 3A and 3B, the consecutive connections or stitch locations between the intermediate knit layer 130 and each of the first and second outer knit layers (e.g., the distance between consecutive stitches 136 for the first outer knit layer 110 and/or the distance between consecutive stitches 138 for the second outer knit layer 120) is represented by distance or course length D2. The distance or course length D2 for consecutive stitch locations along the same outer knit layer can be from about 6 courses to about 12 courses measured along each of the first and second outer knit layers. In example embodiments (such as shown in FIGS. 2, 3A and 3B), each distance or course length D1 between consecutive alternating layer stitch locations is the same, and this also results in the distance D2 between consecutive stitch locations along the same outer knit layer being the same. In alternative embodiments, the distances/course lengths D1 and D2 can differ between different pairs of consecutive alternating layer stitches and between different pairs of consecutive stitches along the same layer.

As shown in FIG. 3A, a distance/course length D3 between consecutive connections or stitches along the intermediate knit layer 130 can be defined by number of courses between consecutive stitches along the intermediate knit layer. The distance/course length D3 can further define a height of the corrugated intermediate knit layer, or a distance between alternating peaks (e.g., peak-to-peak amplitude). The distance/course length D3 can be at least 3 rows or courses along the intermediate knit layer, e.g., from about 4 courses to about 8 courses along the intermediate knit layer).

As previously noted, the distances/course lengths D1, D2 and D3 are defined in terms of rows or courses along the outer knit layers or the intermediate knit layer. Another manner of measuring the distance is based upon a measurement of the actual distance (e.g., in metric length) of the distance between two consecutive stitches. However, it is noted that the Poisson (auxetic or near auxetic) effect achieved for the multi-layered knit structure as described herein is based upon selection of course spacing between the knit layers instead of selection of specific stitch lengths (choosing lengths between stitches).

The intermediate knit layer 130 can be formed as a two way stretch fabric layer (i.e., stretch substantially in only the machine direction or only the cross/width direction of the fabric) or a four way stretch fabric layer. In particular, the intermediate knit layer can possess an elongation (stretch) value that is the same or can vary in the course direction compared with the wale direction of the intermediate knit layer. An elongation value (also referred to as a stretch value) refers to an amount of elongation of a yarn or material in a dimension (length or width) without shearing or breaking that is defined with the formula: [(elongated dimension−original dimension)/(original dimension)]×100. Recovery (elastic recovery or elasticity) is the ability of a yarn or material under load to recover its original size or near original size and shape immediately after removal of the stress that causes deformation. In an example embodiment, the intermediate knit layer can have a dominant degree or amount of stretch or elongation (i.e., greater elongation value) in the course direction (i.e., direction that opposes the wale direction of the first and second outer knit layers, or along the corrugation as shown in FIG. 2 ). In other words, the degree or amount of stretch or elongation (i.e., elongation value) of the intermediate knit layer can be greater in the course direction in comparison to the wale direction of the intermediate knit layer. This can be due to the orientation of the elastomeric yarns and/or the corrugated orientation of the intermediate knit layer. For example, the intermediate knit layer can have an elongation value in the course direction (i.e., direction of the sinusoidal or corrugated pattern as shown in FIG. 2 ) of at least about 50%, e.g., from about 75% to about 250% (ASTM D4964-96 (R2016)). The intermediate knit layer can further have an elongation value in the wale direction of at least about 24%, e.g., from about 30% to about 70%. Alternatively, the intermediate knit layer can have the same or similar elongation values in the course and wale directions.

The first and second outer knit layers can possess an elongation value that are the same or similar to each other and are less than the elongation value of the intermediate knit layer along each of the course and wale directions of the first and second outer knit layers. The first and second outer knit layers can also have the same or different elongation values along their course and wale directions. In an example embodiment, each of the first and second outer knit layers can possess an elongation value along the wale direction for each layer of less than 100% (e.g., no greater than about 50%).

The elongation properties of the layers combined with the corrugation configuration of the intermediate knit layer and the noted distances/course lengths between alternating connection points between the intermediate knit layer and the first and second outer knit layers provides unique stretch and recovery properties for the overall knitted fabric structure 100. In particular, a dynamic textile is formed that is capable of repeated stretching under load and recovery to original or near original size/lengths upon removal of the load. In other words, the stretch properties of the intermediate knit layer, combined with its corrugated shape and connection points (distances/course lengths) between the first and second outer knit layers facilitates a certain amount of overall stretch for the multilayered fabric material under load and, upon removal of the load, further drives the entire fabric material back to its normal, unstretched state.

Referring to FIGS. 4A, 4B and 4C, a schematic of an example embodiment is depicted showing stretching of the multilayered knit fabric structure and how the corrugated intermediate knit layer 130 facilitates stretching along its course direction and along the wale directions of the first and second outer knit layers 110, 120. Referring to FIG. 4A, a portion of the knit fabric structure 100 is depicted in which the structure is in a relaxed state (i.e., not subject to any force or load). In FIG. 4B, a load is applied to the fabric structure 100 causing a stretch in the wale directions of the first and second outer knit layers 110, 120 and a corresponding stretch along the course direction of the intermediate knit layer 130 (due to the connections between the intermediate knit layer and the outer knit layers). The stretch direction is indicated by the double arrows in FIGS. 4B and 4C. As shown in FIG. 4B, as the fabric structure is stretched, the corrugation of the intermediate knit layer 130 (i.e., the amplitude of the corrugated loops) starts to shorten or decrease in dimension. Referring to FIG. 4C, the fabric structure 100 continues to stretch, elongating the outer knit layers and the intermediate knit layer further resulting in further reduction in dimension of the corrugations (amplitude of loops) for the intermediate knit layer. This further decreases somewhat the distance between the first and second outer knit layers (i.e., the fabric structure slightly decreases in thickness).

At some point (e.g., as shown in FIG. 4C), the corrugation of the intermediate knit layer 130 flattens to its full extent, resulting in a “lock out” position or limit in stretch of the fabric structure 100. At this “lock out” position, the fabric structure is prevented or substantially limited in any further stretch capability in the wale direction of the outer knit layers 110, 120. When the tension or load on the fabric structure is released, the fabric structure 100 “snaps back” or recovers to its original (or substantially original) dimensions including the original (relaxed) lengths along the wale direction of the first and second outer knit layers 110, 120 and the course direction of the intermediate knit layer 130 (e.g., the orientation as shown in FIG. 4A). With this configuration, the fabric structure 100 provides a dynamic textile that repeatedly stretches under load and recovers upon removal of the load.

Similarly, referring to FIGS. 5A and 5B, the fabric moves from an unloaded position (no tensile load applied), in which the intermediate corrugations are collapsed (e.g., in contact with each other), to a loaded position upon application of a tensile load (indicated by arrows). As shown, the fabric expands, and the distance/spacing between the corrugations/undulations of the intermediate knit layer increases.

The multilayered knit structure as formed in the manner described herein is provided with stretch properties that, when undergoing stretching (e.g., as depicted in FIGS. 4A-4C), exhibit or impart an auxetic (negative Poisson's ratio) effect or near auxetic (change/decrease in Poisson's ratio) to the knit structure. Knit fabric normally possesses a strongly positive Poisson's ratio; consequently, under load, the fabric will contract in the dimension transverse to the load as shown in FIG. 6A. With the above-described construction, however, the fabric can be configured to possess a lower Poisson's ratio and, as such, a different stretch pattern. Referring to FIG. 6B, knit fabric engineered to possess a strongly negative Poisson's ratio expands in the dimension transverse to the load. In other words, when stretched, the multilayered knit structure will move or expand in a direction generally orthogonal or perpendicular to the applied tension or stretching force. Finally, referring the FIG. 6C, knit fabric engineered with a near auxetic or slightly positive Poisson's ratio may possess a neutral pattern, exhibiting little to no contraction or expansion in the dimension transverse to the applied load (i.e., +/−5% expansion or contraction in direction transverse to load). See FIG. 6C. Stated another way, the multilayered structure will expand in the load direction, but will substantially maintain the same dimension (i.e., will not contract) along the direction orthogonal to the applied tension or stretching force. For example, expansion of the knit structure in the wale direction of the first and second outer knit layers (and course direction of the intermediate knit layer) results in the dimension of the knit structure staying the same (i.e., does not contract, Poisson's ratio decreases but is generally neutral or slightly positive) or a corresponding expansion of the knit structure in the course direction of the outer knit layers and wale direction of the intermediate knit layer (negative Poisson's ratio). In other words, the knit fabric structure will exhibit near auxetic or auxetic properties when stretched in a dimension that corresponds with the direction of consecutive peaks extending along the corrugated shape of the intermediate knit layer. This near auxetic or auxetic effect is achieved via the intermediate knit layer structures within the knit structure. Incorporating such knit structures within articles of apparel provides an enhanced stretching effect for such articles that differs from simply providing elastomeric yarns within the articles. In particular, when a portion of an article of apparel including the multilayered knit structure is stretched in one direction (e.g., along the corrugated surface of the intermediate knit layer), the dimension of the opposing direction either does not substantially change (i.e., does not contract) or actually expands or increases in size (e.g., as shown in FIG. 4D). The multilayered knit structure can further be incorporated within an article of apparel with the corrugation orientation of the intermediate knit layer being aligned in any suitable direction along the article of apparel depending upon an enhanced stretching effect for the article of apparel based upon a particular scenario. The corrugated layer, then, drives the expansion pattern of the knitted composite structure of each outer knit layer such that the entire composite exhibits negative or neutral Poisson's ratio.

An example embodiment of implementing the multilayered knit structure described herein in an article of apparel is depicted in FIG. 7 , in which a brassiere includes the knit structure forming one or more selected portions (e.g., some or all) of the brassiere. As shown, a brassiere 200 includes cup portions or cup areas 210 at the front of the brassiere that incorporate the multilayered knit material structure 100 to enhance stretching/flexure properties in the fabric material at those locations of the brassiere. The brassiere 200 can also incorporate the knit material structure 100 at any other location, such as along the back strap 220 at the rear of the brassiere. The brassiere can further incorporate the knit material structure along a substantial portion (e.g., 50% or more of the bra surface area) or even the entirety of the brassiere. The knit material structure 100 can be implemented within the brassiere 200 in any one or more desired orientations, as referenced by the arrangement of courses (wale direction) of the intermediate knit layer within the structure 100.

Other non-limiting, example embodiments in which the knit material structure is incorporated into apparel products are depicted in FIGS. 8, 9 and 10 . The knit material structure can be implemented within the apparel products in any one or more desired orientations as referenced by the arrangement of courses (wale direction) of the intermediate knit layer within the knit material structure.

An example embodiment is depicted in FIG. 8 , in which the multilayered knit material structure 100 is incorporated within an article of footwear (athletic shoe) 300. For example, the structure 100 can be incorporated along one or more selected areas of the upper for the article of footwear 300 and can further be incorporated into a significant portion of the upper (e.g., incorporated into greater than 50% of the surface area of the upper). Referring to FIG. 8 , the article of footwear or shoe 300 includes an upper 302 comprising a knit material and a sole structure 304 formed of a harder material than the upper. The upper 302 can be formed as a single or unitary knit material. In other embodiments, the upper can be formed of two or more portions that are combined in any suitable manner (e.g., via stitching, adhesive, etc.) to form the upper.

The upper 302 includes a lateral side that aligns with the lateral or outer foot side and a medial side that aligns with the medial or inner foot side of the wearer. In the embodiment of FIG. 8 , a right-footed shoe is depicted with the medial side 315 of the upper 302 being depicted. It is to be understood that a left-footed shoe can have the same or substantially similar features as the right-footed shoe (e.g., with regard to locations at which the knit material structure 100 may be located). The upper 302 and shoe 300 further include a front or toe end 305 and a rear or heel end 310, where the lateral and medial sides of the upper extend lengthwise between the heel and to ends. Each of the lateral and medial sides of the upper further extends from the sole structure 304 upward toward top sections or portions of the upper including a toe cage section 320, an instep section 325, and a collar section 330 that includes an opening to an interior of the upper for receiving and retaining the wearer's foot. Thus, each of the toe cage section, instep section and collar section is located between the lateral and medial sides of the upper and sole structure. The toe cage section 320 of the upper 302 is proximate the toe end 305 and can extend from the toe end to the instep section 325, the instep section 325 is located between (e.g., extends between) the toe cage section 320 and the collar section 330, and the collar section 330 is located proximate the heel end 310 and can extend from the instep section 325 to the heel end. As previously noted, the upper can be formed as two or more portions that are coupled together (e.g., via stitching, adhesive bonding, etc.) or, alternatively, as a single or unitary portion or piece that can be formed to define the various sections (lateral and medial sides, toe cage section, instep section, collar section) of the upper. For example, the instep section of the upper can include a tongue portion that is a separate portion from at least another portion of the upper defining the lateral and medial sides, toe cage section, etc. of the upper. In another example, the instep section is integral or forms a unitary portion with one or both of the lateral and medial sides and with the toe cage section of the upper.

The knit material structure 100 can provide enhanced dynamic stretching, fit and comfort for the wearer of the shoe 300. The knit material structure 100 can be provided at any one or more suitable locations, such as in the toe cage section 320, the instep section 325 (e.g., at or near the tongue portion of the instep section), and at the collar section 320 of the upper 302. Further, the knit material structure can be provided in any one or more suitable orientations within the upper material so as to provide a particular or desired enhanced stretching effect to the upper material at a particular location along the upper. For example, the knit material structure 100 can be oriented at one or more locations at any of the toe cage section 320, instep section 325 and/or collar section 330 such that the course direction of the intermediate knit layer 130 (direction of stretch of the undulating or corrugated shape of layer 130) of the structure 100 is generally aligned along a direction that corresponds with a dimension of the upper 302 that is transverse its lengthwise dimension (i.e., dimension extending between toe and heel end of the upper). Alternatively, the knit material structure 100 can be oriented at any of these sections such that the course direction of the intermediate knit layer 130 is generally aligned in the lengthwise dimension of the upper (i.e., a dimension that extends between toe and heel end). Further, the knit material structure 100 can be provided at a plurality of locations and a plurality of different orientations with regard to how the course direction of the intermediate knit layer of the structure 100 aligns with the lengthwise dimension of the upper.

In another example embodiment depicted in FIG. 9 , an article of apparel that implements the multilayered knit material structure 100 is in the form of an upper body garment or shirt 400 (e.g., an athletic shirt). The shirt 400 includes a torso section (to fit around the torso of the wearer) and two arm sleeve sections (to fit around the arms of the wearer). The knit material structure 100 can be implemented at any portion of the shirt. For example, the knit material structure can be incorporated as part (some or all) of the torso section (as shown in FIG. 7 ). In other embodiments, the knit material structure can be used to form one or more portions of either arm sleeve section and/or the torso section. The knit material structure 100 can further form a substantial portion of the shirt (e.g., covering greater than 50% of the surface area of the shirt). Other portions of the shirt that may not include the knit material structure and can be formed of any textile materials suitable for a shirt and formed via any suitable method and including any suitable one or more types of fibers or strands (e.g., elastic strands, non-elastic strands, polyester strands, nylon strands, etc.). The knit material structure 100 integrated in the shirt 400 can provide enhanced stretching, fit and comfort for the wearer.

In a further example embodiment depicted in FIG. 10 , an article of apparel that implements the knit material structure 100 is in the form of lower body garment 500 (e.g., leggings, pants or shorts). The lower body garment 500 includes a main torso section that is configured to extend around the waist, hip and/or upper thigh regions of the wearer, and further two leg sleeve sections that extend from the main torso section and are configured to extend around some portion of the legs of the wearer. An elastic band can further be provided at an upper edge of the garment 500 around the main torso section. The knit material structure 100 can be implemented at any portion of the lower body garment. For example, the knit material structure 100 can be used to form one or more portions of either leg sleeve section and/or the main torso section. The knit material structure 100 can further form a substantial portion of the lower body garment (e.g., covering greater than 50% of the surface area of the lower body garment). Other portions of the lower body garment that may not include the knit material structure can be formed of any textile materials suitable for a lower body garment and formed via any suitable method and including any suitable one or more types of fibers or strands (e.g., elastic strands, non-elastic strands, polyester strands, nylon strands, etc.). The knit material structure 100 integrated in the lower body garment 500 can provide enhanced stretching, fit and comfort for the wearer.

Other example embodiments incorporating a multilayered knit material structure as described herein are also possible. For example, any textile material product can incorporate the knit material structure as described herein to enhance the stretchable properties of the product.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

For example, the multilayered knit material structure can be implemented in any textile article to enhance stretchability of the article at one or more locations independent of other locations of the article. The knit material structure includes a plurality of layers (e.g., three or more knit layers) that are coupled together and includes at least one knit layer that has a greater degree of elongation in relation to at least one other knit layer.

It is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. It is to be understood that terms such as “top”, “bottom”, “front”, “rear”, “side”, “height”, “length”, “width”, “upper”, “lower”, “interior”, “exterior”, and the like as may be used herein, merely describe points of reference and do not limit the present invention to any particular orientation or configuration. 

What is claimed:
 1. A knit fabric structure comprising: a first knit layer; a second knit layer; and a resilient intermediate knit layer disposed between and coupling with the first knit layer and the second knit layer; wherein the intermediate knit layer has a corrugated shape along a first direction of the intermediate knit layer with consecutive peaks that are oriented in opposing directions such that the peaks comprise a set of first peaks oriented in a first peak direction and a set of second peaks oriented in a second peak direction that opposes the first peak direction, the first peaks of the intermediate knit layer connect with the first knit layer and the second peaks of the intermediate knit layer connect with the second knit layer.
 2. The knit fabric of claim 1, wherein the first knit layer and second knit layer couple with each other only via the resilient intermediate knit layer.
 3. The knit fabric structure of claim 1, wherein a wale direction for the first knit layer is aligned with a wale direction for the second knit layer, and a wale direction of the intermediate knit layer is transverse the wale direction for each of the first and second knit layers.
 4. The knit fabric structure of claim 1, wherein the intermediate knit layer connects with the first knit layer via stitches at the first peaks, the intermediate knit layer connects with the second knit layer via stitches at the second peaks, and a distance D1 between a first stitch at a first peak and a second stitch at a second peak is from about 3 courses to about 6 courses along each of the first and second knit layers.
 5. The knit fabric structure of claim 4, wherein a distance D2 between first stitches of consecutive first peaks connecting the intermediate knit layer with the first knit layer is from about 6 courses to about 12 courses along the first knit layer.
 6. The knit fabric structure of claim 4, wherein a distance D2 between second stitches of consecutive second peaks connecting the intermediate knit layer with the second knit layer is from about 6 courses to about 12 courses along the second knit layer.
 7. The knit fabric structure of claim 1, wherein the intermediate knit layer has a first elongation value in the first direction of the intermediate layer and a second elongation value in a second direction of the intermediate layer that is transverse the first direction, and the first elongation value is greater than the second elongation value.
 8. The knit fabric structure of claim 7, wherein the each of the first knit layer and the second knit layer has an elongation value along a direction of each of the first knit layer and the second knit layer that is less than each of the first and second elongation values.
 9. The knit fabric structure of claim 1, wherein the knit fabric structure exhibits a Poisson's ratio that is negative in response to stretching of the knit fabric structure in the first direction of the intermediate knit layer.
 10. The knit fabric structure of claim 1, wherein each of the first and second knit layers stretches in a direction transverse the first direction of the intermediate knit layer in response to a stretching force being applied to the knit fabric structure in the first direction of the intermediate knit layer.
 11. The knit fabric structure of claim 1, wherein the first knit layer and the second knit layer are formed of yarns comprising polyester.
 12. The knit fabric structure of claim 11, wherein the intermediate knit layer is formed of yarns comprising elastane.
 13. The knit fabric structure of claim 12, wherein the intermediate knit layer is formed of double covered yarns, wherein elastane forms a core of each double covered yarn.
 14. An article of apparel comprising the knit fabric structure of claim
 1. 15. A brassiere comprising the knit fabric structure of claim
 1. 16. An article of footwear comprising the knit fabric structure of claim
 1. 17. The article of footwear of claim 16, further comprising: a sole structure; and an upper comprising a lateral side, a medial side, a toe cage section located proximate a toe end of the upper, a collar section located proximate a heel end of the upper, and an instep section located between the lateral and medial sides and also between the toe cage section and the collar section; wherein the knit fabric structure is provided at one or more of the instep section and the collar section.
 18. The article of footwear of claim 17, wherein the knit fabric structure is provided at a first location and a second location along the upper such that a first orientation of the first direction of the intermediate knit layer for the knit fabric structure at the first location differs from a second orientation of the first direction of the intermediate knit layer for the knit fabric structure at the second location.
 19. A method of forming a knit fabric structure including a plurality of layers, the method comprising: interlooping strands to form a first knit layer; interlooping strands to form a second knit layer; and interlooping strands to form an intermediate knit layer between the first and second knit layers such that the intermediate knit layer couples the first knit layer with the second knit layer, wherein the intermediate knit layer is further formed so as to have a corrugated shape along a first direction of the intermediate knit layer with consecutive peaks that are oriented in opposing directions to define a set of first peaks oriented in a first peak direction and a set of second peaks oriented in a second peak direction that opposes the first peak direction, the first peaks of the intermediate knit layer connecting with the first knit layer and the second peaks of the intermediate knit layer connecting with the second knit layer.
 20. The method of claim 19, wherein the forming of the intermediate knit layer and the coupling of the intermediate knit layer with the first and second knit layers occurs during the forming of each of the first and second knit layers. 